whatever you do, DO NOT buy the pink and white Singer brand one.
The blade is too wide to slip under a stitch. If you do happen to get a thread hooked, the sharp part is in an odd place, not at the base of the V.
However, it is a great "pusher" to guide things while sewing.
I like my Fons & Porter one, but the lid does not stay on. It is larger, ergonomic, so my fibro fingers do not get stressed and achey so quickly. And the red color makes it easy to spot in my tangle.